The invention of which the present disclosure is offered for public dissemination in the event adequate patent protection is available relates in general to surface-working machines, of which one of the most important classes is concrete troweling machines. Troweling machines of the walk-behind type are widely used and are highly satisfactory for small or relatively narrow areas which permit the operator to move the machine to all parts of the surface without stepping on the unset concrete. For larger areas they are subject to the rather serious objection or nuisance caused by the operator's tracks in the concrete. In spite of all that may be done to minimize the track problem, it is usually necessary for the operator to keep working backwards so as to trowel out whatever tracks he produces. A riding-machine for surface-working has been patented, as U.S. Pat. No. 2,869,442, but so far as known it has not proved to be practicable, and it would appear to have serious faults such as inadequate steering. According to the present invention, a thoroughly practicable riding-type troweling-machine (or other surface-working machine) is provided. It uses a plurality of spaced apart troweling rotors, each corresponding to a prior troweling machine. The number preferred in some respects is three, arranged in triangular pattern (however, there can be only two and there could be any number more than three by extending the basic principles and linkages), with the weight of the driving motor and the operator, and the frame and controlling equipment, approximately equally divided among the three rotors. Great stability of action is provided because there can be rather wide inequalities of the weight division among the three rotors without causing any ill effects. If desired, weights may be added for some operations.
Each of the rotors rotates in only one direction and engages the concrete solely with a plurality of trowels, typically three or four, orbiting about the axis of the rotor. The rotationally leading edge of each trowel is curved upwardly and the pitch of all trowels can be controlled during rotation by raising its leading edge, this pitch control being old in individual troweling rotors.
According to the present invention, the direction of movement of the machine and its turning to face in a chosen direction are controlled by selectively applying to one or more of the rotors a tilting pressure. The tilting pressure applies to a chosen side of the rotor an increased pressure of the orbiting trowels on the concrete so that reaction to the increased friction along one side of the orbit exerts a moving force. Most of the time, it is enough that control be exerted through a control stick which the operator can swing forwardly and rearwardly about one axis and left to right about another axis, the movement being universal so that any combination of the two swinging movements may be used. Thus the operator can move the handle straight forwardly for forward movement, straight rearwardly for rearward movement; and with either of these movements can also move the handle sidewise for turning in one direction or the other as the vehicle moves forwardly or rearwardly. If the operator chooses to turn the vehicle with little or no movement forwardly or rearwardly, he can merely move the stick to one side or the other from the neutral position. The stick applies pressure to one rotor in a direction to produce lateral movement by that rotor and simultaneously influences one of the other rotors for forward movement and the other for rearward movement. If crab-like or directly sideward movement is desired, this can be accomplished by applying a pressure to all three rotors at a point selected for inducing movement in a single lateral direction, a foot control applying this pressure to the rotors not given lateral-movement pressure by the stick.
The machine is thus supported entirely by the trowels of its rotors and is nevertheless supported with great stability and may be controlled for all machine movements and steering that could possibly be desired.
Tests have indicated advantages of the apparatus which might be surprising. The results of the troweling in a given time are exceptionally good, perhaps due to the weight of the operator, and the stability of the machine. Of course, the weight of the operator increases the drag on the trowels and requires more power to drive the rotors. Nevertheless, an engine horsepower not much more than three times that common for a single rotor has been found to be sufficient for three rotors with an operator's weight added.
Advantages and objects of the invention will be more clearly apparent from the following description and from the drawings.